High Energy Density Physics with Subpicosecond Laser Pulses最新文献

{"title":"An Accelerating Reference Frame for Electromagnetic Waves in a Rapidly Growing Plasma: Unruh Radiation and the Dynamic Casimir Effect","authors":"E. Yablonovitch","doi":"10.1364/hpslp.1989.m4","DOIUrl":"https://doi.org/10.1364/hpslp.1989.m4","url":null,"abstract":"In 1974, Hawking showed1 that Black Holes can evaporate by the emission of low temperature thermal radiation, now named Hawking Radiation. Shortly thereafter, a closely related effect called Unruh Radiation became apparent. According to Unruh2 and Davies2, observers of the electromagnetic field in an accelerating reference frame should see thermal radiation at a temperature T: where a is the acceleration relative to an inertial frame, c is the speed of light and ħ and K are Planck's and Boltzmann's constant respectively. In a frame accelerating at g= 980 cm/sec2, equivalent to the acceleration experienced at the earth's surface3, this thermal radiation is at a temperature of only 4× 10−20 °K. Therefore, physicists hoping to observe this radiation, have sought out systems being subjected to extreme acceleration. For example, J. S. Bell has suggested4 that the spin depolarization of electrons accelerating around a synchrotron storage ring may be interpreted as being due to such radiation.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1989-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133705656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High Intensity Charge Displacement Self Channeling","authors":"J. Solem, T. Luk, K. Boyer, C. K. Rhodes","doi":"10.1364/hpslp.1989.w6","DOIUrl":"https://doi.org/10.1364/hpslp.1989.w6","url":null,"abstract":"Summary not available.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125111393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Dynamics of Dense Plasmas Produced by Ultra-Short Pulse Lasers","authors":"D. Umstadter, R. Freeman, H. Milchberg, T. Mcilrath","doi":"10.1364/hpslp.1989.pdp4","DOIUrl":"https://doi.org/10.1364/hpslp.1989.pdp4","url":null,"abstract":"The interaction of an ultra-short pulse high intensity laser with a solid target is of current interest because the resulting plasma is also solid density. Such a plasma might be a bright short pulse continuum x-ray source [1] to pump an x-ray laser or probe transient properties such as phase transitions or biological phenomena [2]. Recent experiments [3] have revealed that these plasmas are good continuum emitters and that the continuum x-ray duration is sub-picosecond (streak camera limited). The x-ray pulse width is primarily determined by the rate at which the electrons and the ionization stages cool from the diffusion of heat into the solid and the expansion of material into the vacuum. In the following we report the results of a one dimensional fluid code that models the interaction of an ultra-short laser pulse with a solid target of Aluminum. We describe the dynamics of the mass density, pressure, ionization and expansion velocity. In a related paper we discuss the effects of these quantities on the pulse width of continuum x-ray radiation generated by recombination [4].","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"234 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122829069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral Shifting of Intense Femtosecond Pulses During Strong Field Ionization and Plasma Recombination","authors":"M. C. Downer, W. Wood, W.M. Banyai, J. Trisnadi","doi":"10.1364/hpslp.1989.m5","DOIUrl":"https://doi.org/10.1364/hpslp.1989.m5","url":null,"abstract":"Highly amplified femtosecond pulses permit the study of atomic ionization in superintense light fields on a time scale shorter than the escape time of electrons from the interaction region or the recombination of ionized species. Most recent studies of strong field femtosecond ionization have utilized photoelectron spectroscopy at low gas pressures (~10-7 torr)1. We utilize a complementary experimental method with unique capabilities, namely the spectral blue shift which is caused by the ultrafast refractive index decrease which occurs when a plasma is created within 1 to 20 optical cycles during the pulse2,3. Accurate analysis of such blue shifts requires modelling based on ionization rates calculated from a Keldysh theory4. Because of the ultrashort pulse duration (< 90 fs.), atomic collisions and plasma expansion play no role, compared to experiments with picosecond and longer pulses. Moreover, we have shown3 that in a sufficiently tight focus geometry, contributions from non-ionizing χ(3) processes (e.g.white light continuum generation5, self focusing), which cause both red and blue shifts, are suppressed relative to plasma generation effects2. Thus detailed observation of blue shifts provides a clean diagnostic of strong field ionization which complements photoelectron spectroscopy in testing theories of superintense laser-atom interactions. In addition this technique offers two additional capabilities not easily achieved by photoelectron spectroscopy: 1) It lends itself readily to femtosecond pump-probe experiments, which we report here for the first time. Such experiments allow us to map ionization rate within the temporal profile of a strong pump pulse. In addition, they allow us to measure plasma dynamics (e.g. recombination, expansion) following the ionizing pulse, manifested as a time-delayed probe red shift. 2) In addition this technique is compatible with gas pressures ranging from 0.1 atm. to supercritical densities (> 100 atm.), allowing us to study ionization, recombination, and expansion dynamics at densities in the range (1019 to 1022 cm-3) relevant for X-ray recombination lasers6. At supercritical densities, both forward and backward propagating blue-shifted waves, as well as plasma-confined DC magnetic fields, are generated7. In addition plasma heating7 and relativistic loss mechanisms8 become important. Initial results in this high density regime will be presented.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117077613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"S-Matrix Formulation of High Intensity Multiphoton Processes","authors":"Marvin Mittleman","doi":"10.1364/hpslp.1989.m9","DOIUrl":"https://doi.org/10.1364/hpslp.1989.m9","url":null,"abstract":"Summary not available.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129235121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulations of Intense Laser Beams Interacting with Gases and Solids","authors":"G. Olson","doi":"10.1364/hpslp.1989.pdp1","DOIUrl":"https://doi.org/10.1364/hpslp.1989.pdp1","url":null,"abstract":"The Los Alamos Bright Source Lasers (LABS I and II) are discussed else-where in this conference1 and in previous publications.2 LABS I generates subpicosecond pulses of 5 eV photons with peak intensities of a few 1017 W/cm2, while LABS II operates with shorter pulses at 4 eV and reaches intensities one order of magnitude higher. These lasers have been focused onto gas and solid targets. The purpose of this paper is to discuss numerical simulations of these experiments.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127875200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relativistic Dynamics of Photoelectrons*","authors":"J. Bardsley","doi":"10.1364/hpslp.1989.m7","DOIUrl":"https://doi.org/10.1364/hpslp.1989.m7","url":null,"abstract":"The relativistic dynamics of single electrons in plane-wave electromagnetic fields can be solved exactly, for arbitrary pulse shapes, in both classical and quantum mechanics. Sarachik and Schappert1 (S-S) provided a particularly lucid account of the classical theory, assuming that the electron is at rest before the pulse arrives, and showed that in the relativistic limit the longitudinal component of momentum Pz increases as the square of the electric field strength whereas the transverse momentum pt rises only linearly. The longitudinal momentum is always in the forward direction (PZ > 0) and it oscillates at double the laser frequency. The non-linearities in the relativistic motion lead to the production of high-order harmonics, which become focussed more strongly as the laser intensity is increased. The solution with more general initial conditions was given by Kruger and Bovyn.2","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133388599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiphoton Excitation of Plasma Waves","authors":"S. Rae, K. Burnett","doi":"10.1364/hpslp.1989.w4","DOIUrl":"https://doi.org/10.1364/hpslp.1989.w4","url":null,"abstract":"Recently developed table-top laser sources are capable of producing intensities on target of 1017Wcm\u0000 −2\u0000 in femtosecond pulses. This has stimulated interest in the possible mechanisms for laser light absorption in a plasma produced by such a source. The plasma, expanding at approximately the ion sound speed \u0000 \u0000 \u0000 \u0000 (\u0000 \u0000 \u0000 υ\u0000 s\u0000 \u0000 =\u0000 \u0000 \u0000 Z\u0000 \u0000 k\u0000 B\u0000 \u0000 \u0000 T\u0000 e\u0000 \u0000 /\u0000 \u0000 m\u0000 i\u0000 \u0000 \u0000 \u0000 \u0000 )\u0000 \u0000 \u0000 \u0000 , remains at virtually solid density during the pulse. Light incident on such an overdense plasma boundary will be largely reflected, unless there is strong absorption within the skin depth of the target (~ c/w\u0000 p\u0000 ), where the evanescent wave does penetrate.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123496597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Very High Power Density Subpicosecond Laser for X-Ray Laser Development","authors":"S. Suckewer","doi":"10.1364/hpslp.1989.t8","DOIUrl":"https://doi.org/10.1364/hpslp.1989.t8","url":null,"abstract":"A KrF excimer laser system with a pulse duration of 300 fsec and peak power density of ~1018 W/cm2 is presented. Use of this system for the excitation and ionization of a laser produced, magnetically confined plasma used in the development of a new x-ray laser is discussed.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128453408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"X-Ray Generation from Laser Irradiation of a Thin Film Target","authors":"Harry K. Tom","doi":"10.1364/hpslp.1989.w5","DOIUrl":"https://doi.org/10.1364/hpslp.1989.w5","url":null,"abstract":"Summary not available.","PeriodicalId":417306,"journal":{"name":"High Energy Density Physics with Subpicosecond Laser Pulses","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129346447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}